1. Field of the Invention
The invention relates to an arrangement and method for transporting radicals, for example for removal of contaminant deposits. The invention further relates to a charged particle lithography system comprising such arrangement. The invention further relates to a pressure regulator for connection to a plasma chamber. The invention further relates to a method for transporting radicals.
2. Description of the Related Art
The accuracy and reliability of charged particle lithography systems is negatively influenced by contamination. An important contribution to contamination in such lithography system is caused by the build-up of deposits of contaminants. The charged particles being part of the patterning beamlets and being produced in the system interact with hydrocarbons already present in the system. The resulting Electron Beam Induced Deposition (EBID) forms a carbon containing layer on surface in the system. This layer of carbon containing material influences beam stability. Build-up of such carbon containing layer in and around apertures through which the charged particle beams and/or beamlets pass also reduces the size of the apertures and reduces transmission of beams or beamlets through these apertures. Removal of EBID, in particular in areas with relatively high hydrocarbon partial pressures and relatively high beam current densities, is therefore highly desirable.
Such deposits can be reduced or removed by atom cleaning. This may be achieved using a plasma generator to produce a stream of atoms to react with the deposits. The transport of plasma and the atoms provided therein, in particular radicals, is often inefficient, which may lead to relatively long cleaning periods, and insufficient cleaning quality, i.e. incomplete or inadequate removal of contaminants on a specific surface or a specific volume.